The WNT gene encodes a large family of secreted protein growth factors. During development, Wnt plays different roles in controlling cell fate, proliferation, migration, polarity, and death. In adults, WNT plays an important role in maintaining homeostasis, and abnormal activation of the Wnt pathway is associated with various cancers.
WNT ligands signal through the Frizzled family of 7-transmembrane receptors and the recently discovered LRP5 (low-density lipoprotein receptor-related protein-5) and LRP6 (low-density lipoprotein receptor-related protein-6) co-receptors. Structurally, Frizzled receptors have an extracellular Wnt-binding domain, seven transmembrane regions, and an intracellular C-terminal tail.
Wnt signaling is transmitted through at least three different intracellular pathways, including the canonical Wnt/β-catenin pathway, the "non-canonical" Wnt/Ca2+ pathway, and the Wnt/PCP (planar cell polarity) pathway. The Wnt/β-catenin pathway primarily regulates cell fate during development, while the Wnt/PCP pathway's main function is to regulate cell cytoskeleton organization.
